Organizations increasingly rely on virtualization technologies to improve the flexibility, efficiency, and stability of their data centers. One aspect of virtualization involves provisioning virtual machines with virtual disks for data storage. Virtual disks, like physical disks, may have unallocated space (e.g., unformatted disk regions) and/or unused space (e.g., formatted but unused).
In some scenarios, an organization may wish to back up its virtual machines so that it may recover them in the event of disaster or corruption. However, backing up and restoring a large virtual disk may be time- and resource-intensive. In traditional solutions, a backup system may back up only allocated blocks of data on a virtual disk. However, if an organization did not have a backup system with the capacity to back up only allocated virtual disk blocks at the time of backup, or if the backup system could not identify allocated virtual disk blocks at the time of backup, the organization may be left to restore the entire virtual disk, including unallocated blocks. Furthermore, these traditional virtual machine backup systems fail to improve the efficiency of restoring virtual disks from snapshots. Accordingly, the instant disclosure identifies a need for efficiently recovering virtual machines after disaster scenarios.